1. Field of the Invention
The present invention relates to stringed musical instruments of the type which include an instrument body, a neck extending therefrom and a plurality of strings attached at one end to the instrument body and at the other end to the neck. More particularly, the present invention is directed to an improved system for mounting the neck of the instrument to the instrument body in a manner so that the position of the strings relative to the neck can be easily, quickly and accurately adjusted. The stringed musical instruments in accordance with the present invention may include guitars, such as acoustic guitars, solid body electric guitars and acoustic electric guitars, but may also include other such stringed musical instruments such as, for example, banjos, mandolins, violins, lutes and/or other similar instruments. Although the principles of the present invention will be described herein in connection with guitars, both acoustic and solid body electric, it should be understood that the principles disclosed are also applicable to other stringed instruments which have an instrument body and an elongated neck along which the strings are stretched.
2. Description of the Prior Art
Stringed musical instruments of the type with which the present invention is concerned typically include an instrument body and an elongated neck along which the strings are stretched. In a guitar, the strings are attached at one end to the neck of the instrument, typically by means of tuning keys or tuning machines provided on the end of the neck remote from the instrument body, often termed the "head" of the guitar. The strings then extend over a "nut" provided at the head end of the neck and extend along the neck toward the body. The other ends of the strings are attached either directly to a bridge which in turn is mounted on the body, or to a tailpiece provided behind the bridge mounted on the body and over which the strings extend. In the play of the instrument, the player moves his fingers up and down the neck, clamping the strings so as to shorten them and create various pitches as the strings are strummed, plucked, or otherwise excited. Typically, the neck of the instrument may be covered with a fingerboard which may carry frets thereon extending across the width of the neck so as to provide a means for anchoring the ends of the shortened strings at definite or desired locations.
In the case of an acoustic instrument, such as an acoustic guitar, the body of the instrument encloses a resonant sound chamber. Strumming, plucking or otherwise exciting the strings causes the strings to vibrate. This vibration in turn causes the bridge over which the strings extend to vibrate as well. In fact, the bridge forms the vibrating end point of the strings for every note that is played. Vibration of the bridge in turn causes the top of the acoustic instrument, known as the soundboard, to vibrate as well, which is turn causes air entrapped in the sound chamber to move to generate the sound heard upon play of the instrument. In the case of electric guitars, the instrument body is usually solid, and pickup devices are utilized to convert the string vibration into sound generated by an amplifier or the like. Some types of electric guitars are acoustic electric guitars which will function as an acoustic guitar but can also be provided with a pickup so that acoustic sound is amplified.
There are three general kinds of neck joints which have been used in stringed musical instruments. "Neck-through" instruments have a neck which extends completely through the instrument, and are almost always permanently glued in place. "Set-neck" instruments have a neck which is also permanently glued in place, with a tenon or dovetail joint where the body meets the neck. These instruments usually have a neck heel just forward of the body which extends down to the back of the body to provide support. Finally, there are "bolt-on" instruments which have an opening in the body where the neck overlaps the body, and where bolts are located which join the neck to the body. Generally, in this type of instrument, the neck joint is made solid so that no movement between the neck and body is possible during use of the instrument. However, the bolts can be loosened so that the neck can be removed from or repositioned in the body.
Acoustic guitars are traditionally set-neck instruments, with a neck heel just forward of the body and extending down to the back of the body. This forward protrusion beneath the neck adjacent the body restricts access to the highest region of the fingerboard during play. Electric guitars are commonly either set-neck instruments or bolt-on instruments. Common bolt-on instruments are economical to the construct and repair. However, the drawbacks of the existing bolt-on designs are that the joint has less side-to-side rigidity than glued necks, and access to the highest region of the front of the fingerboard, near the body, is restricted by the body portion extending under the overlap of the neck.
As the bridge of a stringed musical instrument forms the vibrating end point of the strings for every note that is played, it is therefore extremely influential in determining the sound quality of the instrument. In this regard, it is important that the bridge be securely fastened to the top of the body so that it is fixed in place in order to ensure that energy from the vibrating strings is not needlessly lost. Even with solid body electric guitars, the bridge of the instrument still forms the end point of the strings for every note. A loose fitting bridge or one which is not securely fastened to the top will adversely affect the sound quality of the instrument. Also, anything that affects the position of the bridge--longitudinally, laterally, or the height above the top of the instrument--can affect the sound quality of the instrument. (As convenient nomenclature in describing the present invention, the term "longitudinal" is used to denote a direction generally parallel to the direction that the strings extend, and the term "lateral" is used to denote a direction normal thereto but lying generally in or parallel to the plane of the strings. Similarly, the terms "downward" and "vertical" are used to denote a direction generally normal to the plane of the strings and thus normal to the surface of the top of the guitar.)
The height or spacing of the strings above the fingerboard, often referred to as "action", is generally controlled by the height of the bridge and of the nut, as well as the angularity the top surface of the neck relative to the instrument body. In this regard, tilting of the neck downwardly relative to the guitar body serves to bring the strings closer to the fingerboard, and thus lowers the action. Conversely, tilting of the neck upwardly relative to the body tends to move the strings further away from the fingerboard, thus raising the action. The string/fingerboard spacing is generally a matter of personal preference for the player. However, there is a range or window of desirable action for a player, as no player wants an instrument having an excessively high or an excessively low action. The preference is for the player to be able to maintain the action of the instrument as desired. Thus, a limited degree or amount of adjustability of the string/fingerboard spacing is desirable, not only to accommodate individual preferences, but also to accommodate changes in the guitar's response to the effects of time and environment.
The harmonic length of the individual strings of the instrument is generally determined by the distance between the bridge of the instrument located on the body and the nut which is located on the end of the neck remote from the body. Typically, the nut serves as the base reference point in counting the frets, such that the nut is the "zero" fret. The head of the neck may conveniently be angled away or downwardly relative to the fingerboard so as to ensure that the strings rest against the nut and then extend freely over the fingerboard to the bridge. The intonation or harmonic tone of the strings can be changed or adjusted by changing the distance between the bridge and the nut or other anchor point for the strings.
In many solid body electric guitars, the bridge elements may be adjustable longitudinally toward and away from the nut to adjust the intonation of the individual strings. Also, the overall bridge of the instrument may be mounted so as to be moveable longitudinally. In addition, in some instances, the bridge saddles or string support elements may be moved vertically as well to adjust the height or action of the strings. Although adjustable bridges have commonly been employed with electric guitars with satisfactory results, subtle improvements in tone and/or new piezo bridge pickup technologies make the use of a fixed, non-adjustable bridge desirable.
For acoustic guitars, it generally is undesirable to provide an adjustable bridge. Since sound in acoustic guitars is accomplished by driving the soundboard as a result of string vibration, it is desirable to keep the weight of the bridge as small as possible. Making a bridge adjustable would tend to increase the weight, and would change the overall sound quality and would impact on the soundboard serving as an effective sound diaphragm in an acoustic guitar. Moreover, the presence of moving parts in the bridge can lead to some instability which can degrade the sound quality of the instrument.
Accordingly, for these types of reasons as well as the issue of tone quality, most acoustic guitars utilize a fixed, non-adjustable bridge. Moreover, the action (as well as the intonation) of most acoustic stringed musical instruments is set at the factory, and is not readily changeable in the field. This is a significant deficiency of these types of instruments since different players prefer different settings for the action. Furthermore, the wood of which most guitars and the like are constructed is an unstable material, and the action of the instrument tends to vary with atmospheric conditions. For instance, an increase in the humidity tends to cause the top of the instrument to rise due to swelling of the wood, which in turn increases the action of the instrument. Moreover, the top of an acoustic guitar moves up and down seasonally and as it ages.
Consequently, acoustic instruments without action adjustment present a constant problem in that they need to be returned on a periodic basis to the manufacturer or to the place that they were purchased for adjustment, or in some instances, they need to be returned to the manufacturers by the dealer/retail establishment even before any sale. Although the intonation of an acoustic stringed musical instrument is not as sensitive to variations in atmospheric conditions or over time, any changes in intonation which may be desired also typically require return of the instrument to allow relocation of the position of the bridge on the soundboard. It will be appreciated that any return of the instrument, either before it is ever sold by the dealer or when it is returned to the dealer for periodic adjustment, costs time and money.
Therefore, a strong need remains for a system for mounting the neck of a stringed musical instrument to the instrument body in a manner so as to provide for easy and rapid adjustment of the position of the neck relative to the body, and in particular, adjustment of the action of the instrument. Providing an adjustable neck can provide significant cost savings. For instance, at the time of purchase, dealers will be able to maintain optimal action for the instrument irrespective of the seasonal climate, and will be able to adjust the action to meet specific customer preferences. At the factory, providing an adjustable neck joint or system for mounting of the neck to the guitar would permit acoustic guitars to be assembled from complete, pre-finished body and neck sub-assemblies, and then quickly adjusted for ideal intonation and/or action. In this regard, one of the most significant cause of problems and returns of musical instruments concerns the action height, which heretofore could not be easily, rapidly and accurately adjusted. Further, providing an adjustable neck permits one to maintain the height of the bridge on the acoustic instrument without change, which has an important effect on the tonal response for the instrument. Further still, an adjustable neck would be able to accommodate and provide action adjustment to accommodate seasonal and age changes of the instrument over time. Furthermore, the action could be tweaked just before a performance or even between songs if desired. Moreover, with acoustic electric instruments, which may be used either as an acoustic instrument or an electric instrument, providing an easily and quickly adjustable neck would enable a musician to shift in the field from an acoustically powerful high action to a low electric action in a short time. This would allow the acoustic electric instrument to be adjusted optimally for either acoustic play or electric play, providing a level of versatility that guitars have never known.
There are numerous examples in the prior art of devices and systems for adjusting the action of a stringed musical instrument. For instance, U.S. Pat. Nos. 1,889,408; 2,793,556; and 3,302,507 all show examples of stringed musical instruments having mechanisms or devices for varying the inclination of the neck to provide adjustable action, such as by means of a tensioning rod, an adjustable tailpiece and/or the use of shims. U.S. Pat. Nos. 1,707,192, 1,755,019 and 4,172,404 each show stringed musical instruments in which the neck of the instrument is designed to be tiltable at the forward end of the body and in which some type of spring or resilient means is provided for urging the neck toward a particular position. Specifically, in U.S. Pat. No. 1,755,019, a U-shaped spring member constructed of resilient metal is provided for attaching the neck to the body. In U.S. Pat. No. 1,707,192, the neck is joined to the instrument body by means of a hinge pin and a resilient material such as rubber or cork is provided between the neck and the body. In U.S. Pat. No. 4,172,404, the neck is also joined to the instrument body by means of a hinge pin and is urged to pivot thereabout by a coil spring. The orientation of the neck relative to the body is adjustable by means of a slideable plate member having a cam surface engaged by a cam follower provided on an extension of the neck which is urged into engagement with the cam plate by means of the coil spring. Although the devices of such prior art patents are adapted to permit variation in the neck inclination, the constructions as described therein have not proved to be commercially practical, for a variety of reasons, including excessive expense and complexity, insufficient strength or stability, the requirement for excessive clearances, unsightliness, and the inability to adjust intonation as well as the inclination of the neck.
Still other examples of stringed musical instruments having mechanisms or devices for permitting adjustment of the inclination of the neck include U.S. Pat. Nos. 3,196,730; 3,204,510 and 3,550,496, all of which show bolt-on necks. In both U.S. Pat. Nos. 3,196,730 and 3,500,496, the necks are removably secured to the body for means of mounting screws. In order to adjust the orientation of the neck, the mounting screws need to first be loosened to allow pivoting of the neck relative to the body. Adjustment screws must then be either tightened or loosened to thereby set the orientation of the neck in the desired position. The mounting screws then must be retightened to secure the neck to the instrument body. While such arrangements do provide for the desired adjustability of the neck to adjust the action of the instrument, the actual accomplishment of such action adjustment involves a number of operations, involving the loosening of the mounting screws, adjusting the neck and retightening of the mounting screws. Such operations can be both time consuming and can require a certain degree of skill in retightening of components. Still further, there is an inherent amount of play with such arrangements which can lead to degradation of the sound quality of the instrument.
Still other patents which show additional arrangements to provide for adjustment of the neck mounted on the body include U.S. Pat. Nos. 5,679,910 and 5,786,539. Both of these patents show arrangements for providing both action adjustment and intonation adjustment. In particular, intonation changes are accomplished by adjusting the distance that neck projects from the instrument so that there thus is a global change in the intonation or harmonic length of all of the strings of the instrument. Action adjustment of the instrument is accomplished by tilting of the neck of the guitar with respect to the guitar body. Moreover, U.S. Pat. No. 5,786,539 discloses particular mounting arrangements to provide a relatively rigid, solid joint in all directions, including side-to-side stability, by applying pressure simultaneously against fixed horizontal and vertical surfaces. However, even in these arrangements, adjustment of the position of the neck relative to the body is relatively inconvenient and time consuming. Many musicians prefer different action heights for different musical styles, and hence desire a means for changing of the action of their instruments quickly and conveniently, and in some instances even during a performance.
The present invention provides for further improvements in providing for action adjustment, and in preferred embodiments, intonation adjustment and rigid, stable mounting arrangements as well. In particular, the present invention is directed to providing for an easy, rapid adjustment of the action of instrument while accomplishing same in an efficient, economical manner without providing inherent instability for the instrument.